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CA-Physical Science-Simple Machines
Work and Simple Machines
45
Science
8th Grade
11/08/2009

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Cards

Term
Machine
Definition
A device that makes work easier
Term
Direction or size
Definition
Machines make work easier by changing the _______ or ______ of the force you exert
Term
gravity and friction
Definition
Machines try to overcome the forces of ___ and ___ that resists movement of objects
Term
Effort force
Definition
Force that is applied to a machine
Term
Resistance force
Definition
Force that a machine applies to an object
Term
Work input
Definition
Work put into a machine
Term
Work output
Definition
Work exerted by a machine
Term
W = F x d
Definition
Work formula
Term
Ideal machine
Definition
Theoretical machine in which work output is equal to work input due to no friction
Term
Mechanical Advantage
Definition
The number of times a machine multiplies the effort force applied to it
Term
MA = Fr / Fe
Definition
Mechanical advantage formula for any machine
Term
greater than 1
Definition
Machines that multiply the force applied to them have a mechanical advantage that is ____.
Term
equal to 1
Definition
Machines that only change the direction of the effort force have a mechanical advantage that is ___.
Term
less than 1
Definition
Machines that only change the direction of an applied force or the speed at which it moves have a mechanical advantage that is ___.
Term
Simple machines
Definition
Machines that make work easier with just one movement
Term
Lever
Definition
A bar that is free to pivot around a fixed point
Term
Fulcrum
Definition
The point around which a lever rotates
Term
IMA = Le/Lr
Definition
Formula for IMA of a lever
Term
First-class lever
Definition
Lever where fulcrum is positioned between the effort and resistance forces
Term
Second-class lever
Definition
Lever where resistance force is positioned between the fulcrum and effort force
Term
Third-class lever
Definition
Lever where effort force is positioned between the resistance force and fulcrum
Term
Pulley
Definition
Modified lever where a chain or rope runs through a grooved wheel
Term
1
Definition
IMA of a single fixed pulley is ___.
Term
2
Definition
IMA of a single movable pulley is ___.
Term
Block and Tackle
Definition
A system of multiple pulleys
Term
number of ropes supporting the resistance force
Definition
To calculate the IMA of a multiple pulley system, simple count the ____.
Term
Wheel and axle
Definition

A modified lever in which two wheels of different sizes rotate together.

 

 

Term
Wheel
Definition
The effort force is applied to the ____ of a wheel and axle
Term
Axle
Definition
The ___ of a wheel and axle applies the resistance force and is smaller in diameter.
Term
IMA = rw/ra
Definition
Formula for calculating the IMA of a wheel and axle
Term
Gear
Definition
A wheel and axle with teeth
Term
Inclined plane
Definition
Type of simple machine with a sloping surface used to raise objects
Term
IMA = length/height
Definition
IMA formula for an inclined plane
Term
Screw
Definition
An inclined plane that is wound in a spiral around a cylindrical post
Term
Wedge
Definition
An inclined plane with one or more sloping sides that moves through a material to separate it
Term

Levers, pulleys, wheel and axles

 

 

Inclined plane, screw, wedge

Definition
Classify the six simple machines into two groups of related machines
Term
Compound machine
Definition
A machine that is a combination of two or more simple machines
Term
Efficiency
Definition
Measures how much of the work put into a machine is changed to useful work put out of the machine
Term
Wout/Win x 100
Definition
Efficiency formula
Term
Power
Definition
Rate at which work is done
Term
P = W/t
Definition
Power formula
Term
watt
Definition
Power is measured in _____.
Term

 1 Joule/second

 

 

kilowatt

Definition

1 watt is equal to _____.

 

1000 watts is a _____.

Term
heat
Definition
Friction changes the useful work of a machine into ___ energy.
Term
less
Definition
When a machine is used to perform a task, the  work output is always ____ than the work input.
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